The title for this book seemed like a huge spoiler, but I decided to give it a try anyway. All I can really say, without giving the story away, is that the title plays a huge part in the story but not in the way you would initially think. The setting of the story, a small town in Tennesee, is pretty generic for a contemporary story and didn't have any stand out features. This book could have been set in any small town across America. You would assume this would make the story more relatable, but it only makes it less so.
On the other hand. some of the characters were really interesting. For the first half of the book. Outwardly, Luke Grayson, the main character, is very passive. He just let things happen to him and went along with the flow. His inner voice was a different matter. His thoughts were dynamic, sarcastic, and strong. Luke's friend Delilah was a powerful and compelling presence. The other characters were lackluster, including the titular Grant Parker. Then, about halfway through the book, the big confrontation between Luke and Grant happens and things take a turn for the worse. Luke's inner monologue becomes just as flat as his actions. He spends most of the rest of the book drunk and floundering. Delilah all but disappears from the story, leaving an obvious hole in the story.
The bottom line is, this book had a huge amount of potential and, not only does the author play it safe, she actually pulls back in the last half of the book. I really wanted to see more of Delilah. I wanted more detail (and more plausibility) from Luke's parents. In the end, I had to give The Boy Who Killed Grant Parker 2.5 out of 5 stars, and that is overly generous in my opinion.